What happened to Car Radio Antennas?...

[Rob]

David Lesher <wb8foz@panix.com> wrote:

Brian Gregory <void-invalid-dead-dontuse@email.invalid> writes:


AM transmitters with over 50kW output are not used in the US at all.

cough, cough....

WLW. It ran 500KW+ in the past, but regulators cut them back to
the ordinary 50KW level in ~1940.

The transmitter tubes had 3-phase filiments, if that gives you
some idea of their size.

Actually it makes no sense to make an AM (MW) transmitter using tubes
today. Designs using semiconductors and some switching mode are
3+ times more efficient (mains->antenna) and that is a big difference
at those powerlevels.

See e.g. Nautel NX https://www.nautel.com/products/am-transmitters/nx-series/

 

[Rob]

David Lesher <wb8foz@panix.com> wrote:

Brian Gregory <void-invalid-dead-dontuse@email.invalid> writes:


AM transmitters with over 50kW output are not used in the US at all.

cough, cough....

WLW. It ran 500KW+ in the past, but regulators cut them back to
the ordinary 50KW level in ~1940.

The transmitter tubes had 3-phase filiments, if that gives you
some idea of their size.

Actually it makes no sense to make an AM (MW) transmitter using tubes
today. Designs using semiconductors and some switching mode are
3+ times more efficient (mains->antenna) and that is a big difference
at those powerlevels.

See e.g. Nautel NX https://www.nautel.com/products/am-transmitters/nx-series/

 

[Brian Gregory]

On 27/07/2021 09:26, Rob wrote:

Over here, the FM radio network was originally built with horizontal
polarisation. Maybe not much thought was spent on it, and it was done
just the same way as TV was done. Or maybe they had some valid reason
for it that did not work out as expected.

Horizontal polarization is supposedly attenuated slightly less over long
distance.

--
Brian Gregory (in England).

 

[Brian Gregory]

On 27/07/2021 09:26, Rob wrote:

Over here, the FM radio network was originally built with horizontal
polarisation. Maybe not much thought was spent on it, and it was done
just the same way as TV was done. Or maybe they had some valid reason
for it that did not work out as expected.

Horizontal polarization is supposedly attenuated slightly less over long
distance.

--
Brian Gregory (in England).

 

[Ralph Mowery]

In article <slrnsistli.nb4.nomail@xs9.xs4all.nl>, nomail@example.com
says...

You can\'t? Well I can!
- not useful in large parts of the world
- interference from motor control

Probably the interference from the other electronics in the car. Easy
to eliminate if you just leave the receiver out of the radio.

I just hope it is not like a friend that had a car about 40 years ago
where he replaced the spark plug wires and spark plugs with the non
resistor types. If you had an outside TV antenna which almost everyone
did back then you could tell he was on the way from about 3 blocks away
and when he got in the driveway you lost all of the TV station.

 

[Ralph Mowery]

In article <slrnsistli.nb4.nomail@xs9.xs4all.nl>, nomail@example.com
says...

You can\'t? Well I can!
- not useful in large parts of the world
- interference from motor control

Probably the interference from the other electronics in the car. Easy
to eliminate if you just leave the receiver out of the radio.

I just hope it is not like a friend that had a car about 40 years ago
where he replaced the spark plug wires and spark plugs with the non
resistor types. If you had an outside TV antenna which almost everyone
did back then you could tell he was on the way from about 3 blocks away
and when he got in the driveway you lost all of the TV station.

 

[Phil Allison]

Michael Trew wrote:
=============

** All these alternatives to the time honored telescopic whip are compromised.

1. They are *directional* - complete null in two possible orientations.

2. Framed in a steel structure so partially Faraday shielded.

Guess having no ugly antenna sells cars to those who value cosmetics above results.
No wonder the are many \"after market\" alternatives available.


Personally, I\'d rather have a full whip antenna. I owned a \'99 Chevy
(Geo) Metro that had a retractable one.


https://www.youtube.com/watch?v=KuZDVXhdYG8


.... Phil

Haha, not a power one. I can\'t remember the last time I\'ve seen a car
with a power retractable antenna.

** Google \"power antenna\" and you get hundreds of hits for new replacements.
Manual ones went out with the Dodo.

They always seemed to somehow get damaged....


....... Phil

 

[Phil Allison]

Rob the Imbecile wrote:
==================

For some reason, Tesla\'s do not have an AM band.
I can\'t imagine why that is...

You can\'t? Well I can!
- not useful in large parts of the world

** Choke, choke ???
WTF is this idiot on ?


> - interference from motor control

** Obvious reason.
AM radio simply does not work satisfactorily in their wacky contraptions.


...... Phil

 

[Phil Allison]

Rob the Imbecile wrote:
==================

For some reason, Tesla\'s do not have an AM band.
I can\'t imagine why that is...

You can\'t? Well I can!
- not useful in large parts of the world

** Choke, choke ???
WTF is this idiot on ?


> - interference from motor control

** Obvious reason.
AM radio simply does not work satisfactorily in their wacky contraptions.


...... Phil

 

[Phil Allison]

Brian Gregory wrote:
===============

Phil Allison wrote:

you may have noticed that few modern cars have any visible AM/FM antennas these days.
Many have a \"shark fin\" antenna on the roof for GPS and possibly 4G cell phones - frequencies used are similar.
Others have a short whip antenna somewhere, not much good for AM.

I don\'t think a loop aerial on a car window would work at all well
surrounded by the much bigger thinker more conductive loop consisting of
the metal body of the vehicle in which the window is fitted.

** Not true.
AM loops sense the magnetic field of the incoming EM wave.
Some are made from co-ax with the outer shield grounded to eliminate the E field.
Less static noise that way.
The nearby car bodywork has little effect on a window loop.


...... Phil

 

[Phil Allison]

Brian Gregory wrote:
===============

Phil Allison wrote:

you may have noticed that few modern cars have any visible AM/FM antennas these days.
Many have a \"shark fin\" antenna on the roof for GPS and possibly 4G cell phones - frequencies used are similar.
Others have a short whip antenna somewhere, not much good for AM.

I don\'t think a loop aerial on a car window would work at all well
surrounded by the much bigger thinker more conductive loop consisting of
the metal body of the vehicle in which the window is fitted.

** Not true.
AM loops sense the magnetic field of the incoming EM wave.
Some are made from co-ax with the outer shield grounded to eliminate the E field.
Less static noise that way.
The nearby car bodywork has little effect on a window loop.


...... Phil

 

[Michael Trew]

On 7/27/2021 7:24 PM, Phil Allison wrote:

Michael Trew wrote:
=============

** All these alternatives to the time honored telescopic whip are compromised.

1. They are *directional* - complete null in two possible orientations.

2. Framed in a steel structure so partially Faraday shielded.

Guess having no ugly antenna sells cars to those who value cosmetics above results.
No wonder the are many \"after market\" alternatives available.


Personally, I\'d rather have a full whip antenna. I owned a \'99 Chevy
(Geo) Metro that had a retractable one.


https://www.youtube.com/watch?v=KuZDVXhdYG8


.... Phil

Haha, not a power one. I can\'t remember the last time I\'ve seen a car
with a power retractable antenna.

** Google \"power antenna\" and you get hundreds of hits for new replacements.
Manual ones went out with the Dodo.

They always seemed to somehow get damaged....


...... Phil

One would think that the power ones would fail more easily.

 

[Michael Trew]

On 7/27/2021 7:24 PM, Phil Allison wrote:

Michael Trew wrote:
=============

** All these alternatives to the time honored telescopic whip are compromised.

1. They are *directional* - complete null in two possible orientations.

2. Framed in a steel structure so partially Faraday shielded.

Guess having no ugly antenna sells cars to those who value cosmetics above results.
No wonder the are many \"after market\" alternatives available.


Personally, I\'d rather have a full whip antenna. I owned a \'99 Chevy
(Geo) Metro that had a retractable one.


https://www.youtube.com/watch?v=KuZDVXhdYG8


.... Phil

Haha, not a power one. I can\'t remember the last time I\'ve seen a car
with a power retractable antenna.

** Google \"power antenna\" and you get hundreds of hits for new replacements.
Manual ones went out with the Dodo.

They always seemed to somehow get damaged....


...... Phil

One would think that the power ones would fail more easily.

 

[Michael Terrell]

On Saturday, July 31, 2021 at 12:50:55 PM UTC-4, Brian Gregory wrote:

On 29/07/2021 12:35, Rob wrote:
Energy is expensive here and a typical radio station cannot pay the 100kW-1MW
power consumption of an AM transmitter.
AM transmitters with over 50kW output are not used in the US at all.
(There were a handful of experimental ones at one stage in the past)

Yes in Europe higher powers were not uncommon, a few were as high as 1MW.

There was one 500KW AM station, WLW. It was on 700KHz and it operated under an experimental license, and it was shut down in 1939. I saw the site 30 years later, along with the Bethany Ohio VOA site.

http://j-hawkins.com/wlw.shtml

Modern AM broadcast transmitters are a lot more efficient. All solid state, and no separate modulator which operates like a digital audio amplifier. It is built of plug in RF trays that can be hot swapped without shutting down the transmitter. The built in computer monitors the operation of each tray, and lets the staff know that a tray has failed, or can email the engineer if he is off site. Harris Broadcast introduced the first generation in the late \'80s. Harris used to have white papers on their website. You might find them on the \'Wayback Machine\' if you want more details.

 

[Michael Terrell]

On Saturday, July 31, 2021 at 12:50:55 PM UTC-4, Brian Gregory wrote:

On 29/07/2021 12:35, Rob wrote:
Energy is expensive here and a typical radio station cannot pay the 100kW-1MW
power consumption of an AM transmitter.
AM transmitters with over 50kW output are not used in the US at all.
(There were a handful of experimental ones at one stage in the past)

Yes in Europe higher powers were not uncommon, a few were as high as 1MW.

There was one 500KW AM station, WLW. It was on 700KHz and it operated under an experimental license, and it was shut down in 1939. I saw the site 30 years later, along with the Bethany Ohio VOA site.

http://j-hawkins.com/wlw.shtml

Modern AM broadcast transmitters are a lot more efficient. All solid state, and no separate modulator which operates like a digital audio amplifier. It is built of plug in RF trays that can be hot swapped without shutting down the transmitter. The built in computer monitors the operation of each tray, and lets the staff know that a tray has failed, or can email the engineer if he is off site. Harris Broadcast introduced the first generation in the late \'80s. Harris used to have white papers on their website. You might find them on the \'Wayback Machine\' if you want more details.

 

[Michael Trew]

On 7/27/2021 6:26 PM, Brian Gregory wrote:

On 26/07/2021 06:44, Phil Allison wrote:
you may have noticed that few modern cars have any visible AM/FM
antennas these days.
Many have a \"shark fin\" antenna on the roof for GPS and possibly 4G
cell phones - frequencies used are similar.
Others have a short whip antenna somewhere, not much good for AM.

I don\'t think a loop aerial on a car window would work at all well
surrounded by the much bigger thinker more conductive loop consisting of
the metal body of the vehicle in which the window is fitted.

I think it\'d be better to just use it all as a short wire antenna much
like the short whips even for MW and LW.

But most cars nowadays only have FM and DAB+ anyway.

I\'ve never seen a car with a radio without am AM tuner.

 

[Jeff Layman]

On 28/07/2021 07:32, Michael Trew wrote:

On 7/27/2021 6:26 PM, Brian Gregory wrote:
On 26/07/2021 06:44, Phil Allison wrote:
you may have noticed that few modern cars have any visible AM/FM
antennas these days.
Many have a \"shark fin\" antenna on the roof for GPS and possibly 4G
cell phones - frequencies used are similar.
Others have a short whip antenna somewhere, not much good for AM.

I don\'t think a loop aerial on a car window would work at all well
surrounded by the much bigger thinker more conductive loop consisting of
the metal body of the vehicle in which the window is fitted.

I think it\'d be better to just use it all as a short wire antenna much
like the short whips even for MW and LW.

But most cars nowadays only have FM and DAB+ anyway.


I\'ve never seen a car with a radio without am AM tuner.

Perhaps that\'s the difference between the USA and Europe. I can\'t
remember seeing a car radio with MW here in the UK in at least the last
10 years - probably more like 20. Anyway, I miss the standard repair
sometimes seen here many years ago for telescopic antennas - a
\"reshaped\" wire coat hanger!

--

Jeff

 

[Jeff Layman]

On 28/07/2021 07:32, Michael Trew wrote:

On 7/27/2021 6:26 PM, Brian Gregory wrote:
On 26/07/2021 06:44, Phil Allison wrote:
you may have noticed that few modern cars have any visible AM/FM
antennas these days.
Many have a \"shark fin\" antenna on the roof for GPS and possibly 4G
cell phones - frequencies used are similar.
Others have a short whip antenna somewhere, not much good for AM.

I don\'t think a loop aerial on a car window would work at all well
surrounded by the much bigger thinker more conductive loop consisting of
the metal body of the vehicle in which the window is fitted.

I think it\'d be better to just use it all as a short wire antenna much
like the short whips even for MW and LW.

But most cars nowadays only have FM and DAB+ anyway.


I\'ve never seen a car with a radio without am AM tuner.

Perhaps that\'s the difference between the USA and Europe. I can\'t
remember seeing a car radio with MW here in the UK in at least the last
10 years - probably more like 20. Anyway, I miss the standard repair
sometimes seen here many years ago for telescopic antennas - a
\"reshaped\" wire coat hanger!

--

Jeff

 

[Andy Burns]

Michael Trew wrote:

Phil Allison wrote:

Google  \"power antenna\" and you get hundreds of hits for new
replacements.
Manual ones went out with the Dodo.

One would think that the power ones would fail more easily.

I suspect car-washes snapped off more manual ones, with power ones you
could switch off the radio if you realised.

 

[Andy Burns]

Michael Trew wrote:

Phil Allison wrote:

Google  \"power antenna\" and you get hundreds of hits for new
replacements.
Manual ones went out with the Dodo.

One would think that the power ones would fail more easily.

I suspect car-washes snapped off more manual ones, with power ones you
could switch off the radio if you realised.